Varying force counterweight system

ABSTRACT

This invention relates generally to a counterweight apparatus for the purpose of counterbalancing another apparatus to provide previously unavailable typically varying magnitude of force counterweight function when coupled to a scissors lift  2  or similar apparatus. The invention herein described effectively overcomes the problem of counterbalancing the typically varying magnitude of force from a scissors lift  2  or similar apparatus. The unique combination of counterweight  6  movement and changes in the relative location of the sliding support arm&#39;s  3  slidable engaged contact point  9  with the moment arm  5  provides the typically varying magnitude of counterweight  6  force to substantial counterbalance the typically varying magnitude of force from a scissors lift apparatus  2 . Working together these novel features assure substantial continuous counterbalance (neutral equilibrium) will occur in the present invention when coupled to an apparatus with typically varying magnitude of force making it a unique and useful counterweight system.

[0001] This application claims priority of Provisional PatentApplication Ser. No. 60/483,406 filed Jun. 27, 2003.

FEDERALLY SPONSORED RESEARCH

[0002] Not Applicable

SEQUENCE LISTING OR PROGRAM

[0003] Not Applicable

BACKGROUND—FIELD OF INVENTION

[0004] This invention relates generally to counterweight systems,specifically to said counterweight system that provides typicallyvarying magnitude of force counterbalance when coupled to mechanismshaving a typically varying magnitude of force to counterbalance, such asa scissors lift (or similar) apparatus.

BACKGROUND—DESCRIPTION OF PRIOR ART

[0005] With the invention of heavy movable structures such as movablebridges, counterweight systems were also invented to assist in safelyand efficiently managing their heavy loads. Different types ofcounterweight systems were invented, depending on the configuration andcounterbalance needs of a structure.

[0006] Counterweight Systems for Vertical Lift Bridges in Prior Art

[0007] Movable lift bridges, which have high vertical lift movements (50feet or more), have utilized pulley counterweight systems to effectivelyand safely handle their heavy loads. A pulley is a simple machine thatcan be used alone to change the direction of a force. For the longvertical movements of high lift movable bridges, counterweightssuspended by cables passing over pulleys (sheaves) supported at the topof lifting towers is a practical counterbalance design. The followingpatents by L. H. Shoemaker (U.S. Pat. No. 2,482,562) and T. Sakamoto(U.S. Pat. No. 2,040,445) are examples of movable lift bridges withpulley counterweight systems in the prior art.

[0008] Counterweight Systems for Bascular Bridges in Prior Art

[0009] For a movable bascular type cantilever bridge, the bridge deck ismoved to create the draw by rotating the structure vertically (usually70 to 80 degrees from horizontal) to open sufficiently for boats to passand then to close again. For the bascular bridge a counterweight systemis utilized to facilitate the lifting of the heavy deck structure. On amodern bascular bridge the counterweight system is a first class (seesawlike) lever, with a long arm (the bascular deck) and a short arm (thecounterweight), which counterbalance each other when rotated vertically.The nature of the movement (vertical rotation) of bascule bridges issuch that counterbalance can be difficult to achieve. A modern basculebridge is considered well balanced when its counterbalance ensures safebridge operation and machinery performance. The following patents byLucian I. Nedelcu (U.S. Pat. No. 4,751,758) and Ivan Dvorak, ShankarNair and Vinod C. Patel (U.S. Pat. No. 5,454,127) are examples in theprior art of bascular bridges designed with first class levercounterweight systems as described above.

[0010] Early bascule bridge decks were like a door placed horizontalwith a hinge point and no cantilever short arm counterweight. They werelifted by means of ropes attached to the sides toward the extended endof the bascule cantilever deck. Counterbalancing an early design basculedeck was difficult since as the deck was lifted its counterweightrequirements lessened. In 1816 M. Belidor was evidently the first tocompensate for the changing counterbalance requirements of the liftingbascule deck by means of rolling a circular counterweight on a variableslope.

[0011] In the early 1800's Captain Derche also attempted to improvecounterbalance performance for bascular bridges by means of a pulleycounterweight system with a radius of the spiral pulley for compensatingthe changing bascular deck load. As the bascular deck was raised theradius of the spiral decreased in diameter to compensate for thedecreasing load of the deck. The following patents in late 1800's andearly 1900's by Thomas E. Brown (U.S. Pat. Nos. 590,787 and 1,151,657)and Thomas E. Brown, Jr. (U.S. Pat. No. 1,254,773) were basicallymodified pulley type counterweight systems to improve counterbalanceduring a bascular bridge deck's vertical rotational movement, when thelifting points are toward the extended end. These methods ofcounterbalancing a modern bascular bridge were abandoned in favor oflifting the deck at its hinge and to counterweight by means of a firstclass (seesaw like) lever as discussed above.

[0012] Counterweight Systems for Swing Bridges in Prior Art

[0013] For the movable swing type cantilever bridge, the draw (opening)is created by rotating the bridge deck horizontally approximately 90degrees to open sufficiently for marine (or other) traffic to pass andthen to reverse the direction of the rotation to close the draw. Thetypical swing bridge superstructure is supported at its center on aturntable creating a two-armed cantilever bridge deck balanced on saidturntable. Therefore, the swing type cantilever bridge uses a firstclass (seesaw like) lever, with a counterbalanced long arm and a shortarm or two equal length arms of approximately equal weight that rotateshorizontally. The patent to J. B. Strauss (U.S. Pat. No. 1,158,084) isan example of a horizontal swing bridge with a first class levercounterweight system, that rotates horizontally, in the prior art.

[0014] Scissors Lift Apparatus in Prior Art

[0015] Scissors lift apparatus can be found in the prior art. Methods ofimproving the mechanical advantage of the scissor lift have been themain improvements in their designs. Scissor lift or similar apparatushave not been found in the prior art aided by counterweight systems.Utility patents by Michael Schirmer (U.S. Pat. No. 6,257,372 B1),Richard T. Rowan (U.S. Pat. No. 5,722,513) or Haakon G. Egeland (U.S.Pat. No. 3,628,771) are examples of scissors lift apparatus in the priorart.

[0016] To assist the motors with the large force required at the highangle (greater than 45 degrees from vertical) range of its operatingcycle, the patent to Duane R. Franklin and Archibald D. Evans (U.S. Pat.No. 4,558,648) provides a scissors lift apparatus with a sealed gascylinder as an energy storing device. The sealed gas cylinder mechanismprovides force to assist the lifting of a scissors lift apparatus fromits high angle positions; it is not a counterweight system since it doesnot provide stability in the form of neutral equilibrium orcounterbalance (definitions follow) for the mechanism when stopped atany point along its full range of movement.

[0017] In mechanics energy is the capacity to do work. Work is thetransfer of energy. Force is considered as a push or a pull exerted onone body by another. Potential energy from gravity (weight) is a measureof the amount of work a force will do when said weight moves verticallybetween two set points. Potential energy is also the movement of aspring (elastic) and is a measurement of the amount of work a force willdo when said spring moves between two set points.

[0018] Stability is the resistance to any sudden change. Balance is astate in which two opposing forces are of equal strength or importanceso that they effectively cancel each other out and stability ismaintained. Equilibrium is the state in which all forces or processesare in balance and there is no resultant change. A counterweight is aweight that balances another weight. To counterbalance is to have anequal and opposing force or effect on something or to make somethingbalance by putting equal weight on the opposite side. A structure inneutral equilibrium when displaced a small distance will remain stable.A counterbalanced structure can also be said to be in a state of neutralequilibrium since, when free to move, said counterbalanced structuretends to stay in its current position for all normal operatingpositions.

[0019] A counterweighted system is continuously counterbalanced (in astate of neutral equilibrium) when it and the structure it is coupled totends to stay in its current position for all standard operatingpositions. For a counterweight system, neutral equilibrium is achievedwhen the current force from the counterweight is substantially the sameas the current force from the object being counterweighted. Restated, toachieve a continuous state of neutral equilibrium in a counterweightedsystem, the balancing forces in the system remains an approximatelyconstant equal but opposite for all standard operating positions. Forexample in a mechanism with a pulley type counterweight system,counterbalance is achieved by keeping the approximately constant weightin the system substantially equal but opposite by means of a tensioncable over a pulley for all standard operating elevations. Ability toprovide continuous counterbalance or neutral equilibrium between itselfand another apparatus is what defines a counterweight system to be acounterweight system.

[0020] With the invention of the lift-slide drawbridge (patentapplication publication by Rex J. King, Jr. (Pub. No.: US 2003/0221266A1)(Pub. Date: Dec. 4, 2003)), in which the deck is only lifted a fewfeet by means of a scissors lift or similar mechanism, a counterweightsystem is still desirable to safely manage the heavy loads and makepossible the sizing of smaller motors for the system with a resultantoverall cost savings. Since the lift-slide drawbridge's deck is onlylifted a few feet, the use of a pulley type counterweight system ofcables passing over sheaves supported at the top of lifting towers, withthe lifting points of the counterweight system on the deck structure,becomes awkward and is not a practical or efficient counterweightsystem.

[0021] The need to invent a simplified counterweight system to directlyresist the typically varying magnitude of horizontal force from ascissors lift apparatus became apparent when utilizing said scissorslift apparatus to actuate the heavy deck loads of a lift-slidedrawbridge design. The search for a simple means of counterbalance for ascissors lift or similar apparatus led to the novel and unobviouspresent invention. A counterweight system, which when coupled to anapparatus with a typically varying magnitude of force providessubstantially equal but opposite typically varying magnitude of forcefor counterbalance. Until the present invention a simple and reliablecounterweight function for an apparatus with typically varying magnitudeof force such as a scissors lift apparatus (as described above) did notexist.

[0022] A patent search found no prior art of a varying forcecounterweight system for counterbalancing a typically varying magnitudeof force in mechanisms such as a scissors lift or similar apparatus.

[0023] Summary of Prior Art

[0024] After considering first class (seesaw like) lever counterweightsystems utilized on bascule or swing drawbridge structures as disclosedin the prior art and as discussed and cited above, it becomes apparentthat they are not an alternative in counterbalancing a loaded scissorslift (or similar) apparatus.

[0025] After considering the pulley type counterweight systems utilizedon high lift drawbridge structures as disclosed in the prior art and asdiscussed and cited above, it becomes apparent that they are not anefficient or economically effective solution to counterbalancing aloaded scissors lift (or similar) apparatus in which the verticalmovement is only a few feet.

[0026] Accordingly, the present invention of a varying forcecounterweight system provides a novel and unobvious yet simple andreliable counterweight function for a typically varying magnitude offorce, previously unavailable, for scissors lift (or similar) apparatus.The novelty of providing a typically varying magnitude of counterbalanceforce to achieve continuous counterbalance with a typically varyingmagnitude of force from a scissors lift (or similar) apparatus, untilthe present invention, did not exist.

[0027] Therefore, the present invention provides novel and uniquetypically varying magnitude of force counterweight function tomechanisms having a typically varying magnitude of force, such as ascissors lift or similar apparatus.

OBJECTS AND SUMMARY OF THE INVENTION

[0028] The invention herein described when coupled to a scissors lift orsimilar apparatus effectively provides previously unknown typicallyvarying magnitude of force counterweight function for mechanisms havinga typically varying magnitude of force such as scissors lift or similarapparatus. The application of a varying force counterweight systemcoupled with a scissors lift or similar apparatus provides a simplemeans to continuously counterbalance the typically varying magnitude offorce encountered when counterbalancing or lifting even very heavystructures. For example, when coupled with a scissors lift to providecounterbalance and assist in actuating the deck of a lift-slidedrawbridge, the varying force counterweight system has severaladvantages.

[0029] The varying force counterweight system:

[0030] (a) provides neutral equilibrium (continuous counterbalance) forall standard operating positions;

[0031] (b) makes practical the employing of a scissors lift (or similar)apparatus for the lifting of very heavy loads;

[0032] (c) has neutral equilibrium (continuous counterbalance) resultingin minimum external power requirements to actuate the mechanism;

[0033] (d) provides substantially level power requirements throughoutthe operating cycle;

[0034] (e) can be configured in a multitude of ways to effectively meetthe counterweight needs of a project;

[0035] (f) due to unique moment arm configuration, the counterweightsubstantially is lighter than load being counterbalanced;

[0036] (g) is a simple design with few parts making it easy to installand maintain;

[0037] (h) is expected to shorten project construction time due tosimple design; and

[0038] (i) is anticipated to be lower overall in cost of design,materials and construction.

[0039] The present invention is a counterweight system which provides aunique previously unavailable typically varying magnitude of forcecounterweight function when coupled to a scissors lift or similarapparatus by providing a configuration of a rigid body with one degreeof freedom with the main components consisting of (1) a means of supportstructure or frame, (2) a hinged moment arm, (3) a counterweight, (4) asliding support arm, and (5) an means of apparatus with a typicallyvarying magnitude of force to be counterbalanced. A moment arm is theperpendicular distance from an axis point (hinge) to the line of actionof a force.

[0040] An apparatus or mechanism with a typically varying magnitude offorce is an apparatus in which, typically by means of the mechanicaladvantage of a simple machine such as a lever, the input force requiredto resist an output force varies in magnitude. When actuated (moving),depending on the current configuration, the input force may vary fromless than or equal to, to greater than the output force or vice versa asit moves from one end to the other end of its normal range of operation.When static (not moving) the magnitude of the input force will besubstantially constant at a given constant output force. The scissorslift apparatus as proposed in the preferred embodiment of this inventionis a instance if a typically varying magnitude of force which variesfrom less than or equal to, to greater than the output or vice versa asit moves from one end to the other end of its normal range of motion.

[0041] Specifically, in accordance with a the preferred embodiment ofthis invention, a counterweight apparatus when coupled to an apparatusto be counterweighted becomes an interconnected rigid body with onedegree of freedom that remains continuously interconnected when inservice. A rigid body mechanism is a combination of connected parts inwhich all parts remain at fixed distances from one another. A rigid bodymechanism with one degree of freedom requires only one coordinate todescribe the approximate position of one part to be known to determinethe approximate location of each part on the rigid body. The presentinvention's interconnected rigid body with one degree of freedom whenconfigured to specification and with appropriate counterweight achievesa state of neutral equilibrium (continuous counterbalance) which meanssaid structure when static (not moving) tends to stay in its currentposition for all normal operating positions.

[0042] While in motion the present invention also provides work (thepotential energy from the vertical displacement of the counterweight)which assists in balancing the frictional and actuating forces inherentduring said motion resulting in a substantially sustained reduction inpower requirements that are also substantially consistent in magnitude(level).

[0043] A unique and unobvious feature of the present invention is ameans to assure a continuous compressive force connection between thecounterweight side and the load side of the interconnected rigid bodymechanism. This unique and unobvious feature requires both sides of theapparatus to be continuously dependent on a common sliding support armfor their stability (a common compression connection). In other words,the varying force counterweight system (counterweight side) would beunstable and collapse (suddenly move to successive positions of lesspotential energy until stable) without its common coupled connectionwith a scissors lift or similar means of apparatus to be counterweighted(load side) and vice versa. This interdependency, one side leaning onthe other, creates the ability for the system to have the requiredcontinuous compression force on a common sliding support arm. Thisleaning on each other is further assisted by the scissors lift apparatusand the sliding support arm's slidably engaged connection with the meansof support structure resisting vertical movement. The resisting ofvertical movement effectively cancels the vertical component of theforce from the varying force counterweight system and the scissors liftapparatus. The remaining horizontal component of force from the varyingforce counterweight system and the scissors lift apparatus are oppositeand opposing and available to form a required common compressionconnection.

[0044] The required continuous counterweight side of the apparatuspushing (compression force) on the load side of the apparatus and viceversa is a unique feature to the present counterweight invention. Forexample, the opposite is what occurs in a pulley type counterweightsystem where the counterweights pull away (tension force) from eachother with an equal but opposite tension force by means of a commoninterconnecting cable. The double cantilever (seesaw like) counterweightsystems of the bascule and swing bridges are configured to resistancebending or rotational force.

[0045] The horizontal forces from the counterweight side and the loadside of the interconnected rigid body are directed to the slidingsupport arm which is their common connection. Both the counterweightside and the load sides continuous opposite and opposing leaning on thesliding support arm causes a continuous compressive force on this commonconnection assuring it stays in compression but without anotherinnovation it does not achieve the mandatory function of continuouscounterbalance at any point along its range of operation when stationaryand actuated.

[0046] A second unique and unobvious feature of the present invention isalso required to assure continuous counterbalance throughout itsstandard range of operation. This feature provides the ability for thetypically varying magnitude of the force from the counterweight side tocounterbalance the typically varying magnitude of the force from theload side of the interconnected rigid body mechanism. By being able tocontinuously counterbalance the varying magnitude of the force from theload side, the forces in the interconnected rigid body mechanismeffectively cancel each other where continuous counterbalance in theinterconnected rigid body results.

[0047] A third unique and unobvious feature of the present invention isalso required to assure that a continuous varying rate of potentialenergy is provided while in motion throughout its standard range ofoperation. The rate of change of vertical movement varies from maximumvertical movement when the slidably engaged contact point of the slidingsupport arm is at its nearest to the first end of the moment arm anddecreases as it is urged away from said first end of the moment arm andvice versa. This feature provides the ability for a typically varyingmagnitude of the force from the counterweight side to be available whileactuated (in motion), to counterbalance the typically varying magnitudeof the force from the load side of the interconnected rigid bodymechanism and to assist in balancing the frictional and actuating forcesinherent during actuation. By being able to continuously counterweightthe varying magnitude of force from the load side, the majority of theforces in the interconnected rigid body mechanism remain substantiallycounterbalanced during said motion resulting in a substantiallysustained reduction in power requirements and substantially consistent(level) power requirements.

[0048] To explain the present inventions ability to provide a typicallyvarying magnitude of counterweight force we must envision how a scissorslift or similar apparatus having a typically varying magnitude of forceis configured. A first arm of a scissors lift and a second arm of saidscissors lift apparatus are identical. The first and second arms of thescissors lift are pivotally linked to one another at their centralpoints. The first arm's upper end is rotationally fixed to a beam andthe second arm's upper end is slidably engaged to said beam. The secondarm's lower end is rotationally fixed to a lower support structure andthe first arm's lower end is slidably engaged to said support structure.The first arm's upper rotationally fixed end is configured to maintain aposition substantially above the second arm's lower rotationally fixedend. The second arm's upper slidably engaged end is configured tomaintain a position substantially above the first arm's lower slidablyengaged end.

[0049] All four ends of the two arms of the scissors lift allow forrotational movement. The first arm's upper rotationally fixed endresists horizontal movement of the beam. The second arm's lowerrotationally fixed end resists horizontal movement of the scissors liftapparatus. The beam coupled to the upper ends of the first and secondarms of the scissors lift apparatus is now configured to be actuated upand down relative to the support structure by means of applying ahorizontal actuating force (R) to said first arm's lower slidablyengaged end.

[0050] Therefore, given the above configuration, if full range ofmovement of a scissors lift apparatus is from 20°≦θ≦57° from thevertical for all values of θ₁<θ₂ the corresponding values of thehorizontal actuating force (R) at the first scissors lift arm's lowerslidably engaged end is R₁<R₂ consistently throughout the defined fullrange of movement of said scissors lift apparatus. This means that thelower the scissors lift apparatus is (the greater the angle fromvertical) the larger the required counterbalance force to resist thehorizontal actuating force (R) and provide neutral equilibrium to thesaid scissors lift apparatus. Restated, to counterbalance a scissorslift apparatus with the above configuration the opposite and opposingcounterweight force will need to simultaneously increase or decrease asthe horizontal actuating force (R) from said scissors lift apparatusincreases or decreases.

[0051] In accordance with another preferred aspect of this invention,the counterweight apparatus comprises a means of support structure witha first end of a moment arm hinged to said means of support structure. Acounterweight is attached to the second end of said moment arm. Asliding support arm is slidably engaged with said moment arm. Thesliding support arm is structured to be simultaneously slidably engagedto and support the moment arm, slidably engaged with the supportstructure and pivotally linked to the scissors lift apparatus. Thevarying force counterweight system's sliding support arm is pivotallylinked to the scissors lift apparatus at the scissors lift's lowerslidably engaged end. The sliding support arm is slidably engaged withthe means of support structure to provide for stability, therefore, asneeded, guides and flanged wheel trucks are provided along the slidingsupport arm. The result of the sliding support arm's slidably engagedconnection with the means of support structure is that the verticalmovement of said sliding support arm is resisted. The resisting of thevertical movement effectively cancels the vertical component of theforce from the varying force counterweight system. The remaininghorizontal component of force remains to resist the opposite andopposing horizontal force from the scissors lift apparatus.

[0052] The moment arm is configured to be slidably supported by thesliding support arm along a predetermined line of contact between thefirst and second ends of said moment arm. A drive means forbidirectional (back and fourth) actuating of the sliding support arm iscoupled to said sliding support arm or another convenient location.Bidirectional actuation increases or decreases the magnitude ofavailable counterbalance force to the scissors lift apparatus. Thetypically varying magnitude of force is due to the lowering or rising ofthe center of gravity (at a varying rate) with the decreasing orincreasing the respective relative distances between the slidablyengaged contact point of the sliding support arm with the first andsecond ends of the moment arm during bidirectional actuation. When themovement of the slidably engaged contact point of the sliding supportarm is toward the direction of the second end of the moment arm(counterweight end), the scissors lift apparatus rises and thecounterweight lowers, at a varying rate, resulting in a decreasing ofthe magnitude of the force from the counterweight to the sliding supportarm which substantially matches the decreasing magnitude of force fromthe rising said scissors lift apparatus. When the movement of theslidably engaged contact point of the sliding support arm is toward thedirection of the first end of the moment arm (hinged end), the scissorslift apparatus lowers and the counterweight rises, at a varying rate,resulting in an increasing of the magnitude of the force from thecounterweight to the sliding support arm which substantially matches theincreasing magnitude of force from the lowering said scissors liftapparatus.

[0053] The unique combination of varying rate of counterweight verticalmovement and changes in the relative location of the sliding supportarm's contact point with the moment arm provides the typically varyingmagnitude of counterweight force to counterbalance the typically varyingmagnitude of force from a scissors lift apparatus. As a result thevarying force counterweight system achieves the required continuouscounterbalance (neutral equilibrium) in the interconnected rigid body ofthe present invention.

[0054] The basic nature of the present invention is the application of acombination of mechanical principles not previously understood capableof being combined for the purpose of counterbalancing mechanisms.Depending on the mechanism being counterbalanced, the counterweightsystem of present invention may require reconfiguring. It can thereforebe appreciated the final configuration of a varying force counterweightsystem coupled with an apparatus to be counterweighted will varydepending on the nature of said apparatus to be counterweighted. Forexample, in some applications the source of the potential energy fromthe counterweight (potential energy from gravity) may be replaced with aspring (elastic potential energy).

[0055] The means of apparatus to be counterweighted may comprise anymeans of apparatus which requires a varying magnitude of counterbalanceforce to be continuously counterbalanced, such as the scissors liftspreceded in utility patents by Michael Schirmer (U.S. Pat. No. 6,257,372B1), Richard T. Rowan (U.S. Pat. No. 5,722,513) or Haakon G. Egeland(U.S. Pat. No. 3,628,771).

[0056] The means of actuation of a varying force counterweight systemcoupled with a scissors lift or similar apparatus may comprise any meansof actuation which is capable of actuating the mechanism such as ahydraulic ram.

[0057] Preferably the means of sliding includes guides and flanged wheeltrucks. The means of sliding may comprise of any mechanism capable ofproviding the needed sliding (or straight line motion).

[0058] The means of pivotal link of the present invention with ascissors lift or similar apparatus may comprise any means of pivotallink which provides for the required connection movements and may beplaced in a state of continuous compression for the full range ofoperation of the present invention.

[0059] In accordance with an alternate embodiment of this invention, amoment arm is adjustable in length. On movable bridge structures thedeck load on the scissors lift apparatus is almost constant andadjustment in the varying force counterweight system is seldom needed.Adjustment in the varying force counterweight system for movable bridgestructures can easily be made by adding or removing a portion of thecounterweight.

[0060] In some applications of the varying force counterweight systemthe load on the scissors lift apparatus will be different with eachlift. As the load on the scissors lift apparatus changes, thecounterweight on the varying force counterweight system must also beadjusted. By adjusting the length of the moment arm the magnitude offorce from the counterweight available for counterbalance of thescissors lift apparatus can also adjusted.

[0061] In accordance with another alternate embodiment of thisinvention, the initial distance between the pivot axis of the moment armand the initial contact point of the moment arm can be adjusted to tunethe system to perform according to a required specification. Therefore,the initial distance between the pivot axis of the moment arm and theinitial contact point of the moment arm is adjustable.

[0062] In accordance with another alternate embodiment of thisinvention, an interconnected rigid body with one degree of freedomapparatus with a varying force counterweight system is transportable.For some applications such as movable bridge structures, the relocationof the varying force counterweight system is seldom needed. Any requiredadjustment in the position of the interconnected rigid body with onedegree of freedom apparatus with a varying force counterweight systemcan easily be made by designing minor adjustment into the supportstructure.

[0063] In other applications, an interconnected rigid body with onedegree of freedom apparatus with a varying force counterweight systemwill need to be relocated continuously. For these applications theinterconnected rigid body with one degree of freedom apparatus supportstructure can be designed into a skid, with wheels or rollers, orslidably engaged or fixed to a secondary means of transport.

[0064] In accordance with another alternate embodiment of thisinvention, varying force counterweight systems are placed in seriesand/or in parallel to one another. For some applications such as movablebridge structures, space or other limitations or special varying forcerequirements may require the linking a plurality of varying forcecounterweight systems in series and/or in parallel with one another toobtain a desired varying magnitude of counterweight force function.

[0065] While the preferred embodiments of the invention have beenillustrated and described, it will be appreciated that various changescan be made therein without departing from the spirit and scope of theinvention.

SUMMARY

[0066] In accordance with the present invention, a varying forcecounterweight system is a counterweight system which provides previouslyunavailable typically varying of force counterweight function whencoupled to a scissors lift or similar apparatus by providing aconfiguration of a rigid body with one degree of freedom with the maincomponents consisting of (1) a means of support structure or frame, (2)a hinged moment arm, (3) a counterweight, (4) a sliding support arm, and(5) an apparatus with a typically varying magnitude of force to becounterbalanced. When properly configured a varying force counterweightsystem has at least three novel and unobvious features to ensurecounterweight function when coupled to an apparatus with a typicallyvarying force to be counterbalanced.

[0067] The first novel and unobvious feature is the means to assure thecommon connection between the counterweight and the load side of theinterconnected rigid body mechanism of the present invention is alwaysin compression (force). By providing a common sliding support arm whichthe opposite and opposing forces from both sides of the mechanism relyon for stability, the required compression connection is always present.

[0068] The second novel and unobvious feature of the present inventionassures continuous counterbalance (neutral equilibrium) in theinterconnected rigid body of the mechanism by means of the presentinventions unique counterweight and hinged moment arm's continuousreconfiguration during movement which provides instantaneous changes inthe magnitude of the force delivered by the counterweight system.

[0069] The third novel and unobvious feature of the present inventionassures continuous varying rate of potential energy is provided to theinterconnected rigid body mechanism while in motion. Restated, whenactuated the present inventions unique counterweight and hinged momentarm configuration also moves vertically at a varying rate providingpotential energy at a varying magnitude of force to assist the means ofactuation. This feature provides assistance in balancing the frictionaland actuating forces inherent during actuation resulting in a sustainedreduction in power requirements and substantially consistent (level)power requirements.

[0070] Working together the novel features of the present inventionassure counterbalance (neutral equilibrium) will occur, making it aunique and useful counterweight system when coupled to an apparatus witha typically varying magnitude of force to be counterbalanced.

DRAWINGS

[0071] Drawing Figures

[0072]FIG. 1 illustrates an elevation view of a preferred embodiment ofthe invention showing the varying force counterweight system pivotallylinked to a scissors lift apparatus with said scissors lift apparatus inthe lowered position.

[0073]FIG. 2 illustrates an elevation view of a preferred embodiment ofthe invention showing the varying force counterweight system pivotallylinked to a scissors lift apparatus with said scissors lift apparatus inthe raised position.

PREFERRED EMBODIMENTS OF THE INVENTION

[0074] The operation of the varying force counterweight system 1consists of a bidirectional (back and forth) sliding movement; whenactivated (in motion) to the left the sliding support arm 3simultaneously lifts the scissors lift apparatus 2 and said slidingsupport arm's 3 slidably engaged contact point 9 with the moment arm 5moves left providing a simultaneous decreasing of the magnitude of thecounterbalancing force. To lower the scissors lift apparatus 2 theprocess is reversed. When stationary (not moving) the varying forcecounterweight system 1 provides substantially constant neutralequilibrium (continuous counterbalance) function.

[0075] FIGS. 1-2—Preferred Embodiment

[0076] The preferred embodiment of the present invention is illustratedin FIGS. 1-2 elevation views. A support structure 4 is provided suchthat when a varying force counterweight system 1 and a scissors liftapparatus 2 or similar apparatus are coupled to said support structure 4and interconnected to each other they become an interconnected rigidbody with one degree of freedom apparatus 21 that remains continuouslyinterconnected by means of a sliding support arm 3 while in service.

[0077] A means of support structure 4 may be a frame, a foundation orany structure capable of providing the support necessary for theapparatus to become an interconnected rigid body with one degree offreedom 21.

[0078] A moment arm 1 with said moment arm's first end 7 hinged to asupport structure 4. A counterweight 6 is attached to the second end ofsaid moment arm 8. A sliding support arm 3 is slidably engaged with andsupporting the moment arm 5. The sliding support arm 3 is structured tobe simultaneously slidably engaged with the moment arm 5 between thefirst 7 and second 8 ends of said moment arm 5; slidably engaged withthe support structure 4 with a sliding support 10; and pivotally linkedto the scissors lift apparatus 2 at the lower scissors lift arm'sslidably engaged end 19.

[0079] The result of the sliding support arm's 3 slidably engagedconnection or sliding support 10 with the means of support structure 4is that the vertical movement of said sliding support arm 3 is resisted.The resisting of the vertical movement effectively cancels the verticalcomponent of the force from the varying force counterweight system 1.The remaining horizontal component of force is directed to resist thehorizontal force from the scissors lift apparatus 2.

[0080] The sliding support arm 3 is slidably engaged with said means ofsupport structure 4 to provide for stability, therefore as and whereneeded a means of guides and flanged wheel trucks 15 are coupled to thesliding support arm 3.

[0081] When a varying force counterweight system 1 is coupled to ascissors lift apparatus 2 by means of a sliding support arm 3, saidsliding support arm 3 is configured to cancel the opposite and opposinghorizontal component of the their respective forces sufficiently tocause a counterbalancing of the loads of the overall mechanical system.The operation of the varying force counterweight system 1 consists of abidirectional movement of a sliding support arm 3 between the varyingforce counterweight system 1 and the scissors lift apparatus 2. When themovement of the sliding support arm 3 is in the direction of thescissors lift apparatus 2, said scissors lift apparatus 2 is raised asshown in FIG. 2 and when the movement of the sliding support arm 3 is inthe direction of the varying force counterweight system 1 said scissorslift apparatus 2 is lowered as shown in FIG. 1.

[0082] The moment arm 5 is configured to be slidably engaged andsupported by the sliding support arm 3 between an initial contact point11 and a final contact point 12 which are located between the first 7and second ends 8 of said moment arm 5. The rightmost point of operationis when the scissors lift table 14 is at its lowest point and thesliding support arm 3 is slidably engaging the moment arm 5 at theinitial contact point 11. The leftmost point of operation is when thescissors lift table 14 is at its highest point and the sliding supportarm 3 is slidably engaging the moment arm 5 at the final contact point12.

[0083] At the rightmost point of operation the elevation of thecounterweight 6 and the distance from the center of gravities of saidcounterweight 6 and the moment arm 5 to the initial contact point 11where said moment arm 5 is being slidably engaged is maximum. In thisconfiguration the maximum magnitude of force from the varying forcecounterweight system 1 is obtained.

[0084] At the leftmost point of operation the elevation of thecounterweight 6 and the distance from the center of gravities of saidcounterweight 6 and the moment arm 5 to the final contact point 12 wheresaid moment arm 5 is being slidably engaged is minimum. In thisconfiguration the minimum magnitude of force from the varying forcecounterweight system 1 is obtained.

[0085] The rate of change of vertical movement varies from maximumvertical movement when the slidably engaged contact point 9 is at itsnearest to the initial contact point 11 decreasing as it is urged awaytoward the final contact point 12 and vice versa.

[0086] In a general explanation, when actuated the current slidablyengaged contact point 9 of the sliding support arm 3 with the moment arm5 moves from right to left as its relative spatial relationship with thefirst 7 and second ends 8 of the moment arm 5 and the counterweight 6continuously change and the magnitude of force from the varying forcecounterweight system 1 decreases. The centers of gravity also movedownward at a varying rate providing a varying magnitude of potentialenergy to the system. The decrease in the magnitude of the force is dueto the simultaneous results of the leftward movement. The oppositeoccurs when the current slidably engaged contact point 9 of the slidingsupport arm 3 moves from left to right. The means of actuation can behydraulic rams H coupled to the sliding support arm 3 or anotherwell-situated point of actuation.

[0087] A scale model of an interconnected rigid body with one degree offreedom apparatus 21 consisting of a scissors lift apparatus 2 and avarying force counterweight system 1 was built and initial tests usingit are consistent with the previous explanation of the mechanics. Thescale model was constructed with a 38 lb. moment arm 5 with a center ofgravity located approximately four (4) feet from the pivot axis of saidmoment arm 13. A series of tests were conducted with approximately 150lbs. of load L (weight) on the scissors lift apparatus 2 (includingself-weight). The angle of moment arm 5 varied from 16.5°≦α≦8.5° fromhorizontal.

[0088] In the first test, the varying force counterweight system 1 wasuncoupled from the scissors lift apparatus 2 and the horizontal reactionR required to lift said scissors lift apparatus 2 over the full range ofmovement of said scissors lift apparatus 2 (54°≦θ≦25°) from vertical wasobserved. The maximum horizontal reaction R required to lift thescissors lift apparatus 2 over its full range of movement was greaterthan 150 lbs.

[0089] In the second test, the varying force counterweight system 1 wascoupled to the scissors lift apparatus 2 with the 38 lb. moment arm 5slidably engaged with the sliding support arm 3. With no additionalcounterweight 6 added to the varying force counterweight system 1, themaximum additional horizontal force R required to lift the scissors liftapparatus 2 over its full range of movement was reduced to 140 lbs. Theinterconnected rigid body with one degree of freedom apparatus 21 wasnot operating in neutral equilibrium (not counterbalanced).

[0090] In the third test a 37 lb. counterweight 6 was placed on themoment arm resulting in a combined total counterweight 6 ofapproximately 75 lbs. with a center of gravity located approximately 5.8feet from the moment arm's 5 pivot axis of the moment arm 13. Themaximum additional horizontal force R required to lift the scissors liftapparatus 2 over its full range of movement was 30 lbs. and theinterconnected rigid body with one degree of freedom apparatus 21 wasoperating in neutral equilibrium (continuous counterbalance).

[0091] When operating in neutral equilibrium in the third test, theinterconnected rigid body with one degree of freedom apparatus 21provided an 80% reduction in energy requirement compared with thescissors lift apparatus 2 uncoupled from the varying force counterweightsystem 1. If similar results are obtained on a large scale scissors liftapparatus 2 with a total load weighting 300 tons the power required tolift the scissors lift apparatus 2 approximately 3.5 feet in 30 secondswould be approximately 29 horsepower.

[0092] In another series of tests, it was observed that the magnitude ofthe force required to lift the scissors lift apparatus 2 dropped inproportion to the counterweight 6 added to the moment arm 5.Counterweight 6 was incrementally added to the moment arm 5 until theinterconnected rigid body with one degree of freedom apparatus 21 beganoperating in neutral equilibrium. More weight was incrementally added tothe counterweight 6 and the interconnected rigid body with one degree offreedom apparatus 21 continued to operate in neutral equilibrium(continuous counterbalance) until the horizontal force R to lift thescissors lift apparatus 2 was reduced to zero (0) and the scissors liftapparatus 2 tended to lift on its own. These observations demonstratethat the interconnected rigid body with one degree of freedom apparatus21 operates in neutral equilibrium over a large variation in the weightof the counterweight 6, given a fixed load on the scissors liftapparatus 2, revealing the present invention to be a very stable andeasy to operate counterweight system.

Reference Numerals in Drawings

[0093]1 varying force counterweight system

[0094]2 scissors lift apparatus

[0095]3 sliding support arm

[0096]4 means of support structure

[0097]5 moment arm

[0098]6 counterweight

[0099]7 first end of the moment arm

[0100]8 second end of the moment arm

[0101]9 slidable engaged contact point

[0102]10 sliding support

[0103]11 initial sliding contact point

[0104]12 final sliding contact point

[0105]13 pivot axis of moment arm

[0106]14 scissors lift table

[0107]15 flanged wheel trucks

[0108]16 scissors lift first arm

[0109]17 scissors lift second arm

[0110]18 scissors lift arm's rotationally fixed end

[0111]19 scissors lift arm's slidably engaged end

[0112]21 interconnected rigid body with one degree of freedom apparatus

[0113] L load

[0114] H hydraulic cylinder

[0115] R horizontal force

[0116] θ scissors lift arm's angle from vertical

[0117] α moment arm angle from horizontal

[0118] FIGS. 1-2—Alternative Embodiments

[0119] In accordance with an alternate embodiment of this invention, thevarying force counterweight system 1, the load L on the scissors liftapparatus 2 will be different with each lift. As the load L on thescissors lift apparatus 2 changes, the counterweight 6 on the varyingforce counterweight system 1 must also be adjusted. By adjusting thelength of the moment arm 5 the magnitude of force from the counterweight6 available for counterbalance of the scissors lift apparatus 2 can alsobe adjusted.

[0120] The means of adjusting the length of the moment arm 5 maycomprise any means which permits the shortening or lengthening of saidmoment arm 5.

[0121] In accordance with another alternate embodiment of thisinvention, the initial distance between the pivot axis of the moment arm13 and the initial contact point 11 of the moment arm 5 can be adjustedto tune the system to perform according to a required specification.Therefore, the initial distance between the pivot axis of the moment arm13 and the initial contact point 11 of the moment arm 5 is adjustable.

[0122] The means of adjusting the initial distance the pivot axis ofmoment arm 13 and the initial contact point 11 of the moment arm 5 maycomprise any means which permits the adjustment of the components.

[0123] In accordance with another alternate embodiment of thisinvention, an interconnected rigid body with one degree of freedomapparatus 21 with a varying force counterweight system 1 istransportable. For some applications such as movable bridge structures,the relocation of the varying force counterweight system is seldomneeded. Any required adjustment in the position of the interconnectedrigid body with one degree of freedom apparatus 21 with a varying forcecounterweight system 1 can easily be made by designing minor adjustmentinto the support structure.

[0124] In other applications, an interconnected rigid body with onedegree of freedom apparatus 21 with a varying force counterweight system1 will need to be relocated continuously. For these applications theinterconnected rigid body with one degree of freedom apparatus 21support structure 4 can be designed into a skid, with wheels or rollers,or slidably engaged or fixed to a secondary means of transport.

[0125] The means of transport of a an interconnected rigid body with onedegree of freedom apparatus 21 with a varying force counterweight system1 may comprise any means of transport which permits the relocation ofthe mechanism from one location to another.

[0126] In accordance with another alternate embodiment of thisinvention, varying force counterweight systems 1 are placed in seriesand/or in parallel to one another. For some applications such as movablebridge structures, space or other limitations or special varying forcerequirements may require the linking a plurality of varying forcecounterweight systems 1 in series and/or in parallel with one another toobtain a desired varying magnitude of counterweight force function.

[0127] The means of linking a plurality of varying force counterweightsystems 1 in series and/or in parallel with one another to obtain adesired varying magnitude of counterweight force function may compriseany means of linking which obtain the required counterweight function.

[0128] While the preferred embodiments of the invention have beenillustrated and described, it will be appreciated that various changescan be made therein without departing from the spirit and scope of theinvention.

[0129] Conclusion, Ramifications, and Scope

[0130] The need to invent a simplified counterweight system to directlyresist the typically varying magnitude of horizontal force R from ascissors lift apparatus 2 became apparent when utilizing said scissorslift apparatus 2 to actuate the heavy deck loads of a lift-slidedrawbridge design. The search for a simple means of counterbalance for ascissors lift 2 or similar apparatus led to the novel and unobviouspresent invention. A counterweight system, which when coupled to anapparatus with a typically varying magnitude of force provides equal butopposite typically varying magnitude of force for counterbalance. Untilthe present invention, counterweight function for an apparatus withtypically varying magnitude of force such as a scissors lift apparatus 2did not exist.

[0131] Although the description above contains much specificity, theseshould not be construed as limiting the scope of the invention but asmerely providing illustrations of some of the presently preferredembodiments of this invention. Depending on the configuration and thetypical varying magnitude of the force of a mechanism the varying forcecounterweight system 1 is coupled to, variations in the design will berequired. For example, it may be of benefit to use a spring to supplypotential energy for counterbalance rather than the weight ofcounterweight 6, etc.

[0132] Thus the scope of the invention should be determined by theappended claims and their legal equivalents, rather than by the examplesgiven.

What is claimed is:
 1. A counterweight apparatus with a typicallyvarying magnitude of counterbalance force, comprising: a supportstructure; a moment arm, first end of said moment arm is hinged to thesupport structure; a counterweight, said counterweight attached to thesecond end of said moment arm; a sliding support arm, said slidingsupport arm slidably engaged to said moment arm while slidably engagedwith said support structure; and a drive means for actuating saidcounterweight apparatus; whereby bidirectional sliding of said slidingsupport arm while slidably engaging said moment arm provides anincreasing or decreasing magnitude of counterbalance force on saidsliding support arm.
 2. The apparatus of claim 1 further comprising asupport structure that is transportable.
 3. The apparatus of claim 1,wherein a plurality of counterweight apparatus are coupled with saidcoupling selected from the group consisting of series and parallelcouplings.
 4. The apparatus of claim 1, wherein the moment arm isadjustable in length.
 5. The apparatus of claim 1, wherein the locationof the sliding support arm's slidably engaged connection with the momentarm is adjustable.
 6. The apparatus of claim 1, further comprising aplurality of slidably engaged connections disposed along and coupled tothe sliding support arm, to slidably engage the support structure viasaid slidably engaged connections.
 7. The apparatus of claim 1, whereinthe sliding support arms slidably engaged connections are selected fromthe group consisting of wheel trucks and slides.
 8. The apparatus ofclaim 1, wherein the counterweight is selected from the group consistingof weights and springs.
 9. A counterweight apparatus forcounterbalancing a means of apparatus with a typically varying magnitudeof force, comprising: a frame; a moment arm, first end of said momentarm hinged to said frame; a counterweight, said counterweight fixed tosecond end of said moment arm; and a sliding support arm, is slidablyengaged with said moment arm, while pivotally linked to said means ofapparatus with a typically varying magnitude of force and slidablyengaged with said frame; whereby continuous typically varying magnitudeforce from said counterweight apparatus and said means apparatus with atypically varying magnitude of force counterbalance each other.
 10. Theapparatus of claim 9 wherein the means of apparatus with a typicallyvarying magnitude of force is a scissors lift apparatus.
 11. A method ofproviding a typically varying magnitude of counterweight force to anapparatus with a typically varying magnitude of force for the purpose ofcontinuous counterbalancing comprising the steps of: support a first endof moment arm with a hinged connection; attach a counterweight to thesecond end of said moment arm; support said moment arm, on said slidingsupport arm with a slidably engaged connection between said first andsecond ends of said moment arm; pivotally link said sliding support armto said apparatus with a typically varying magnitude of force; and slidesaid sliding support arm; whereby continuous counterbalance is provided.12. A method of providing a interconnected rigid body with one degree offreedom apparatus with capacity for continuous substantial neutralequilibrium throughout normal range of operation, comprising the stepsof: construct a support structure; construct a unstable rigid body withone degree of freedom mechanism with a typically varying magnitude offorce; construct a unstable rigid body with one degree of freedomcounterweight mechanism with a typically varying magnitude of force; andattach to said support structure said unstable rigid body with onedegree of freedom mechanism with a typically varying magnitude of forceand said unstable rigid body with one degree of freedom counterweightmechanism with a typically varying magnitude of force arranged andconfigured with their movements opposite and opposing andinterconnecting with a pivotal link; whereby capacity for continuoussubstantial neutral equilibrium throughout normal range of operation isprovided.
 13. A method of providing a continuous varying in magnitude offorce to a mechanism with a typically varying magnitude of force,comprising the steps of: construct a support structure; support a firstend of a moment arm with a hinged to said support structure; attach acounterweight to the second end of said moment arm; support said momentarm between the first and second ends of said moment arm with a slidingsupport arm arranged and configured with the sliding movement of saidsliding support arm being substantially parallel to the longitudinalaxis of said moment arm; slidably support said sliding support arm withsaid support structure; and couple said sliding support arm to saidmechanism with a typically varying magnitude of force arranged andconfigured with their movements opposite and opposing; whereby slidingof said sliding support arm initiates a continuous varying in magnitudeof force to said mechanism with a typically varying magnitude of force.14. A counterweight apparatus for counterbalancing a means of apparatuswith a typically varying magnitude of force, comprising: a means ofmoment arm; a means of hinging first end of said moment arm to a meansof support; a means of counterweight; a means of coupling said means ofcounterweight to second end of said means of moment arm; a means ofsliding support arm; a supporting of said means of moment arm on saidmeans of sliding support arm with a means of slidable engagement; ameans of sliding said means of sliding support arm on said means ofsupport; a means of coupling said means of sliding support arm to saidmeans of apparatus with a typically varying magnitude of force; a meansof actuation; and a means of adjusting weight on said means ofcounterweight apparatus until said means apparatus of with a typicallyvarying magnitude of force is counterbalanced; whereby a means ofcontinuous substantial counterbalance is provided.
 15. A counterweightapparatus for counterbalancing a means of apparatus with a typicallyvarying magnitude of force, comprising: a support structure; a momentarm, first end of said moment arm is hinged to the support structure; asliding support arm, said sliding support arm slidably engaged to saidmoment arm, slidably engaged with said support structure and pivotallylinked to said apparatus with a typically varying magnitude of force;and a drive means for actuating said counterweight apparatus; whereby aincreasing or decreasing the relative location of said sliding supportarm's slidably engaged connection with said moment arm's first andsecond ends, initiates a raising or lowering of the center of gravity ofsaid moment arm; whereby continuous typically varying magnitude of forcefrom said counterweight apparatus and said means of apparatus with atypically varying magnitude of force counterbalance.